مجله فیزیولوژی و فارماکولوژی ایران
سال دوم شماره 2 (پیاپی 6، تابستان 1397)

Chloride channels are present in mitochondrial membranes where they regulate volume and acidity of cells and organelles, cell signaling, and protective mechanisms of the cells. We have previously reported the presence of a 301 pS chloride channel in mitochondrial inner membrane of the rat brain. In this work we characterized biophysical properties of a new chloride channel in the mitochondrial inner membrane of the rat brain.

The rat brain was harvested and homogenized in the MSE-nagarase lysis buffer. The homogenate was centrifuged in 3 steps in MSE-digitonin, H2O, Na2CO3, respectively. Vesicles of mitochondrial inner membrane were then extracted in MSE solution. The membrane lipid L-α-Phosphatidylcholine was extracted from fresh egg yolk. Bilayer lipid membrane was formed in a 200 μm diameter hole.  All recorded data were filtered at 1 kHz and stored at a sampling rate of 10 kHz for offline analysis by PClamp10 software. Statistical analysis was performed by Markov's noise-free single channel analysis.

Channel incorporation into planar lipid bilayer revealed a selective anion channel with a conductance of 158 pS in 200 mM KCl cis/50 mM KCl trans electrolyte. The channel open probability appeared to be voltage dependent as the channel was very active at the voltages between ± 20 mV. Adding the chloride channel inhibitor DIDS in the side corresponding to the cell internal medium (cis) caused a strong inhibition of the channel activity.

Our results indicate the presence of a chloride channel in the mitochondrial inner membrane of the rat brain. This channel might play a role in maintaining proper pH level, regulation of membrane potential, ATP synthesis, and cell protection.

Vitiligo, psoriasis and some skin cancers are due to abnormal melanogenesis and disturbance in melanocytes homeostasis. Aryl hydrocarbon receptor (AHR) is a ligand-dependent transcriptional factor involved in many physiological processes including drugs metabolism, development of immune system, cellular homeostasis, regulation of cell cycle, and as an essential factor in melanogenesis. The aim of this study was to investigate whether the NADPH oxidases (NOXs) system can interfere with the normal function of aryl hydrocarbon receptor in melanogenesis.

B16/F10 mouse melanoma cell line were cultured in DMEM and treated with different concentrations of the endogenous ligand of AHR, 6-formylindolo[3,2-b] carbazole (FICZ) (1-100 nM) alone or in combination with an AHR antagonist 3'-Methoxy-4'-Nitroflavone, MNF, or cytochrome P450 type CYP1A1 inhibitor, or a NADPH oxidase (NOX) inhibitor, curcumin (1µM), for different time periods. The activity of CYP1A1 and tyrosinase enzymes as well as total melanin level were measured at the end of treatments.

CYP1A1 enzyme activity was induced in B16/F10 cells by FICZ in a dose and time dependent manner. Tyrosinase activity and melanin level also were increased by FICZ 100nM. Importantly, treatment of the cells with combination of FICZ 1nM and curcumin induced melanin synthesis.

Taken together, inhibition of metabolic degradation of FICZ might elicit biological/toxicological effects on skin homeostasis.

Learning and memory play a key role in daily human life. Memory is the basis of all teaching and training programs. Identification of compounds that improve learning and memory would be helpful for people with mental and memory impairment. This study aimed to evaluate the effects of physical training and essential oil (EO) of Matricaria chamomilla on passive avoidance memory in rats.

Forty-six rats (250-300g) were randomly divided into 6 groups of 8 animals, including control group, group that received 50 mg/kg M. chamomilla EO, group that received 75mg/kg M. chamomilla EO, group that received physical training +50 mg/kg M. chamomilla EO, groups that received physical training +75 mg/kg M. chamomilla EO. Animals were treated with physical training and M. chamomilla EO for 10 days. Passive avoidance learning was evaluated after the 6th EO administration for 4 days using shuttle box apparatus. Blood samples were then collected and serum antioxidant capacity was determined.

In passive avoidance test, there was no significant difference between experimental groups in initial latency. The secondary latency in groups receiving 75 mg/kg EO, physical training, physical training+50 mg/kg EO and physical training +75 mg/kg EO was significantly higher than the control group. Serum antioxidant capacity in physical training and physical training +75 mg/kg EO groups were higher than the control group.

Physical training and chamomile essential oil alone or in combination improve learning and memory in rats.

Morphine has a high addictive potential and can be abused. Long-term use of morphine is associated with some pathological consequences including neurotoxicity, neuronal dysfunction, oxidative stress and apoptosis. Increasing evidence has shown that melatonin has antioxidant and antiapoptosis properties. However, its effects on morphine-induced neurotoxicity in PC12 cells have not been studied. This study was carried out to evaluate protective effect of melatonin against morphine-induced neurotoxicity in PC12 cells.

PC12 cells were treated for 24 h with several doses of melatonin (10, 25, 40, and 50 μM). The cells were then treated with 3.2 mM morphine for 24 h. The viability of PC12 cells was measured using MTT assay. The antioxidant activity of melatonin was evaluated by measuring the levels of reactive oxygen species (ROS), lipid peroxidation (LPO) and total thiol groups, and total antioxidant power (TAP).

Melatonin significantly enhanced the viability of PC12 cells and protected the cells against morphine-induced overproduction of ROS. Melatonin has increased TAP and total thiol groups and decreased LPO.

Melatonin attenuates neurotoxicity of morphine in PC12 cells via antioxidant activity.

Alzheimer’s disease (AD) is a neurodegenerative disorder that can cause memory loss, personality changes and unusual behavior. The purpose of this study was to investigate the effect of ampakine Farampator on impairment of working memory in rat model of Alzheimer's disease.

Forty male Wistar rat (250-300g) were randomly divided into five experimental groups including: Group 1: Sham/control (intra-hippocampal microinjection of phosphate buffer solution (PBS)/1μl); Group 2: Rat model of Alzheimer's disease (intra-hippocampal microinjection of 4μg/1μl amyloid beta 1-42), Groups 3 & 4: Rat model of Alzheimer's disease + Farampator (30 and 300 µg/kg/by oral gavage/ twice per day); Group 5: Rat model of Alzheimer's disease + Farampator vehicle (saline/ by oral gavage / twice per day). Y-maze spontaneous alternation test was used to evaluate the working memory.

Intra-hippocampal injection of amyloid beta 1-42 caused significant defects in working memory in rat model of Alzheimer's disease (p < 0.01). Farampator 300 µg/kg significantly improved working memory task in rat model of Alzheimer's disease (p < 0.05). Farampator 30 µg/kg had no significant effect on working memory impairment in rat model of Alzheimer's disease.

Ampakine farampator can improve the working memory defect in rat model of Alzheimer's disease.

It has been reported that menopause is associated with increased oxidative stress and subsequent memory deficits and anxiety. According to the antioxidant property of Ascorbic Acid (AA), we tested the effect of AA on oxidative stress, impairment of working memory and anxiety like-behavior in ovariectomized mice.

Forty-eight female mice weighting 20 ± 5 g were randomly divided into six groups of eight including AA control group, sham, untreated ovariectomized, and ovariectomized treated with the doses of (100, 300, 500 mg/kg, by oral gavage for 1 month) of AA. Then, working memory (by T-maze), anxiety like-behavior (by Elevated Plus-maze) and the activity of Glutation peroxidase (GPx) in mice brain tissues were determined.

AA by the doses of 100 (p < 0.05) and 500 mg/kg (p < 0.001) improved working memory of ovariectomized mice compared to untreated ovariectomized group. AA by the doses of 300 and 500 mg/kg increased Open Arm Time (%OAT) of ovariectomized animals compared to untreated ovariectomized group (p < 0.01). Open Arm Entries (%OAE) were also increased in ovariectomized treated group by the dose of 300 (p < 0.01) and 500 mg/kg (p < 0.001) of AA. The activity level of GPx increased in ovariectomized mice treated by AA 500 mg/kg compared to untreated ovariectomized group (p < 0.01).

AA especially at the dose of 500 mg/kg showed a significant improvement in anxiety, working memory as well as the level of GPx activity in ovariectomized mice.

Studies have shown that performance-enhancing drugs (PEDs) especially anabolic steroids cause liver damage. There is no study on the PEDs effects on the liver of bodybuilding athletes in Bushehr city (Iran).  Aim of this study was to evaluate the hepatic effects of PEDs, particularly anabolic steroids in male bodybuilders in Bushehr.

Demographic information, exercise program, use of PEDs, alcohol and dietary supplements were recorded in male bodybuilders using a questionnaire. Participants were divided into three groups: 1) current users (CU), 2) non-current users (NCU), and 3) non-users (NU). The serum levels of alanine transaminase (ALT), aspartate transaminase (AST) and bilirubin were measured in the athletes by using the commercially available kits. The data were analyzed by using one-way analysis of variance.

Two-hundred and three bodybuilders with the age range of 18-50 years, body mass index of 18.6-40 kg/m2, and average of 6 years exercise were included in the study. In the present study, 8.9% of athletes were current users, 39.9% were non-current users, and 51.2% were non-users. Athletes have been used anabolic steroids, stimulants, growth hormone, and insulin. The average period of PEDs use in athletes was 60 days/year by simultaneous oral and injection routes. The serum levels of ALT (p = 0.003), AST (p = 0.000) and bilirubin (p = 0.023) were significantly different between the three groups. The serum levels of ALT (p = 0.000) and AST in current users were higher than non-user athletes, while only the AST level in non-current users was higher than non-users (p = 0.044).

The use of anabolic steroids with other PEDs may raise the serum level of hepatic enzymes in male bodybuilders. This effect may be the sign of PEDs-induced hepatic injury in these athletes.

Thyroid hormones play a role in cell growth regulation, metabolism, and body trace elements. These hormones, copper and zinc are effective on fertility. The aim of this study was to evaluate the effect of thyroid function on the amount of copper and zinc in rat seminal plasma.

Twenty four male Wistar rats divided in 3 groups (n = 8) including: control group, hypothyroid groups which treated by methimazole low dose (20 mg in 100 ml of drinking water) and which treated by methimazole high dose (100 mg in 100 ml of drinking water). At the end of a 42-day treatment period, blood samples were taken from animals under deep anesthesia. Serum samples were collected from blood, and semen plasma samples were collected from seminal vesicle. The body and testis of animal were weighted. Hematocrit (HCT) was determined. Serum levels of thyroxin hormone (T4) were measured by Radioimmunoassay. The content of the Copper (Cu) and Zinc (Zn) in the seminal plasma was determined with inductively coupled plasma optical emission spectrometry.

Methimazole decreased the serum T4 level (p < 0.001), Zn in the seminal plasma (p < 0.001) and relative weight of the testes (p < 0.01) in a significant and dose-dependent manner. Hematocrit level decreased in two hypothyroid groups (p < 0.001). The testis weight and Cu in the seminal plasma reduced in the high dose treatment group (p < 0.01).

Methimazole or hypothyroidism induced by methimazole attenuated zinc concentration in seminal plasma, testes relative weight and Hematocrit level. However, copper reduction in the seminal plasma occurred only by high dose of methimazole.